Introduction & Project Summary

For the MAE 277 course project, our group chose to purchase our desired product in order to work with a mechanical product that we all have an interest in learning more about. As a group we were initially split between preferring to dissect an auto engine or piece of consumer electronics, so we met halfway with the choice of an RC car. Specifically, our product is the \'\'\'1/10 2.4 Ghz Exceed Hyper Speed Beginner Version .16 Engine Nitro Powered Off Road Buggy Blue Fire\'\'\'. This is a beginner model Nitro RC car designed by Exceed-RC meant for recreational or competitive use both on and off road.

For the first gate of the project, we analyzed the product as a whole, examining its subsystems and functions as a whole. Not much information was gathered at this point of the project but more importantly, we set up a plan which allowed the rest of the work for the rest of the gates to proceed without conflict.

The second gate of the project focused on dissecting the car in order to analyze it further. Once the car was completely taken apart, we were able to analyze the various forms of connections which were present in the car. These connections range from a screw connecting two pieces, to the axles which connect different items of the drive train and allow energy to flow between different parts of the car. We found that the four factors play a large part in the ways which the parts are connected and for this product economic factors are far more prevalent than the other three in the design. This is because the Hyper Speed is a beginner model which consumers are not expected to spend large sums of money on maintaining.

The individual components were analyzed in the third gate of the project. We found that most of the parts on the car were made from injection molding as there are a lot of plastic parts with visible part lines. Once again, this is an example of economic factors at work in the project. Any part which did not need to be durable was made with a lightweight, inexpensive polymer. We then looked at parts which could be revised in order to improve the quality of the buggy. Most of the revisions we proposed in the third and fourth gates have a larger cost than those which are on the beginner model. By our dissection and analysis of the components, and the reassembly of the product, it is clear that this beginner car was designed around the concepts of ease of use and cost-effectiveness.

Project Gates

Gate 1: Project Planning

Management Proposal

In order to properly execute the dissection and analyze our RC car, our group has set up a schedule for meeting which will allow us to discuss and compare individual pieces of each gate. We plan to meet on Saturday afternoons for around an hour. At these meetings we will discuss what we have each written for the upcoming gate in order to avoid redundancy or contradictions between members. In the case of disagreements, it will fall to the Head Researcher to fact check in order to decide which group member is correct. For the dissection itself, we will meet for several hours on Saturday, October 15th as we believe we can dissect the product entirely with tools that we already have. Should an impasse arise, we will figure out a time to utilize the extra tools in the dissection lab in the week following. The individual roles we have chosen can be seen below in Table 1.

For each individual gate, the written work will be divided as evenly as possible amongst the group members. Ideally, each member will have a piece to write which is closely related to their part in the project. Individual written parts are to be emailed to Craig three days before the gate is due in order to leave sufficient time for the document to be edited and formatted as a technical report. A detailed timeline for the remainder of the project can be seen by clicking on the link Work Timeline. As we go ahead in this project, we will need to develop skills as a group. The main aspect of the project which we are not strong with is wiki management. This will be easy to learn as there is much information on the web. Otherwise, the main challenges come from learning how to analyze an individual component and figure out how it was designed from the finished product. By using in class materials, we should be able to progress properly in this area as the project moves forward.

Work Proposal

As seen in the work timeline, we have Saturday, October 15th planned as the date which we will be dissecting our RC car. The process by which we are planning to do this can be found in the wiki for Disassembly Steps.

The tools that will be required for this process are a standard size Philips head screwdriver, a small Allen-wrench set, and a small wrench. These will suffice to remove all visible fasteners, but some other tools may be necessary which we cannot anticipate until we begin the dissection process. We believe that we will need around 2 hours in order to dismantle the car and properly document the process which we execute. Some of the factors which are working towards the success of are group and against it are shown in Table 2, located below.

\'\'\'Capabilities\'\'\'

\'\'\'Shortcomings\'\'\'

We are all familiar with the operation of RC cars

None of us have ever taken apart an RC car

The car was designed for easy interchangeability

No group experience working with car systems

Tools required are easily accessible outside the dissection lab

Difficult to tell what may be required for dissection past the external parts

Product Archaeology

Gate 2: Product Dissection

Preliminary Project Review

Our initial management and work proposals have been moderately successful as a template for successfully completing the required work for this project. The process of splitting the work up evenly and meeting to discuss individual parts of the gates is definitely efficient to maintain a standard of quality and a uniform style between all parts of the gate. Each group member has been contributing their parts on time thus far, and no conflict has arisen due to late work. However, as we failed to detail the consequences for late work in gate 1, we have decided together that if a group member shows up to a meeting without their part of the gate which we are discussing, we will all make note of it in order to be honest about who carried their weight properly in the final project evaluations.

The biggest problem with management which our group has faced is a major time crunch before the due date of Gate 1. The original plan, quoted from the management proposal was that "Individual written parts are to be emailed to Craig three days before the gate is due in order to leave sufficient time for the document to be edited and formatted as a technical report." This turned out to not be a proper amount of time as editing the wiki is more work than we anticipated, especially when adding in pictures and tables. Our solution to this is to move the due date of individual pieces of two days up. We now plan to meet five days before the gate is due to discuss what members need to do more editing to finalize their written work, and the next day everyone will email their work to Craig to be put together and onto the wiki. This leaves an entire weekend for wiki management, allowing for better work and less stress. The only remaining problem which we foresee at this time is that the next gate requires some more specific skills, such as CAD proficiency and properly performing engineering analysis. We need to discuss as a group at our next meeting who would be best suited for which task.

For the dissection of the RC car, we were not able to perfectly follow or work proposal. The main reason for this was that it simply took more time than we anticipated.
In the amount of time we had initially planned to work, we only finished removing all of the subsystems from one another. We required another two hours the following day in order to dismantle the subsystems into their individual component parts. This is partially because when writing up our disassembly steps, we were unable to anticipate how many components were in each of the subsystems, which contributed all of the extra time. However, we were correct in our assumption that we could dismantle the car to its components without the use of any tools not owned by group members which allowed us to easily find the time in the dorms to do this. After the dissection, we faced a major setback when we lost a majority of the pictures which we had taken due to file corruption. Because of this, not all of the pictures shown in the product dissection of this gate are from the dissection itself. We remedied this by retaking a batch of pictures after the fact in order to fill in the gaps as best as possible which we feel represent the steps which we took properly.

Dissection

The dissection of the RC car was performed in two separate processes. The first was the removal of all of the subsystems from the one another. This process took about two hours to complete and is detailed below. The second process was the dissection of the subsystems into their individual components. This also took just over two hours and is detailed in the linked wiki Dissection of Exceed RC Buggy Subsystems.

The entire car is intended to be disassembled. The modular design of this car allow the use to swap out broken parts as well as upgrade individual parts of the car to increase performance. With the exception of the tires and servos the entire car is intended to be disassembled. The servos have sensitive electronics inside that we do not want to break and the tires of the car are plastic welded to the harder plastic rim

The metric which we used to gauge the difficulty of each step is as follows:
1 - Fastener is removable with ease, typically with only one hand
2 - Requires two hands or extra force, but still relatively easy to safely remove component
3 - Requires caution to remove properly. May require two people to remove safely
4 - Not designed to be taken apart by the consumer but can be safely removable with a good deal of effort
5 - Part cannot be removed without damaging the function of the car

\'\'\'Step #\'\'\'

\'\'\'Part\'\'\'

\'\'\'Dissection Process\'\'\'

\'\'\'Tools Used\'\'\'

\'\'\'Difficulty\'\'\'

\'\'\'Image\'\'\'

1

Spoiler

Remove two pins and the four screws that connect the spoiler to the frame.

The engine and fuel tank are spaced out on the right side of the frame to keep the hot engine away from the flammable fuel. The weight of these two components is offset on the other side by the batteries, computer and reciever. These subsystems are shown in Figure 2.

It is easiest to describe the connections between the other subsystems by tracking energy, signal, and mass flows and determining sources. In respect to signals, the “source” doesn’t respond to the production of the signals but rather the central hub for distributing signals throughout the car. The fuel tank is the source of fuel for the car. The Servo (computer/receiver) system is the source of the signals for the car. The intake/exhaust is the source for air for the car.

All electric signals are implemented using wires while most other connections involve metal fasteners.

The fuel tank is connected to the engine and intake/exhaust by two plastic tubes much like surgical tubes. These tubes allow air to enter the fuel tank and allow fuel to leave.

The servo system is connected to the engine via the throttle. The throttle works to send physical signals from the servos to control the engine’s performance. The throttle is also connected to the transmission, but upon dissecting the car it became evident that this connection was only present so that the throttle could rotate around a pin. There is no direct connection between the servos and transmission. The Servo system is also connected to the wheels by rotating joints and arms. The purpose of this connection is to turn the wheels.

The engine is connected to the servos, intake/exhaust, fuel tank, and transmission. The engine’s connection to the servos is through the throttle as described above. The fuel tank is connected to the intake/exhaust and the fuel tank by tubes. These tubes allow for fuel and air to enter the engine and for excess gases to exit through the exhaust. The engine is connected to the transmission by the drive train. The drive train is a shaft that is rotated by the engine and transfers energy to the transmission through gears. The transmission is connected to the engine and the differentials. Energy enters the transmission from the engine through two gears and exits the transmission to the differentials through two rotating shafts. The differentials are connected to each wheel by a “dog bone” shaft which turns the wheels.

\'\'\'Influence of the Four Factors:\'\'\' The connections between the subsystems are all universally recognizable. The screws used to connect the subsystems to the frame are all standard Phillips head screws which addresses global concerns of manipulation and customization of the car. It can be run in dirt and mild rain without stopping due to the enclosed gear boxes and fuel system. As long as the engine still has access to air, the car will run. The axle and drive shaft connections along with the gearboxes, the chassis and many other parts are made of metal, keeping wear-and-tear to a minimum on the parts that are subjected to the most abuse which addresses economical concerns.

\'\'\'Performance Considerations:\'\'\' All drive shafts work using ball and socket joints with a pin through the ball allowing it to transfer rotational energy. This allows the drive shafts to continue to function as the car’s suspension changes the level of the tires with changing terrain. Other performance considerations present in the implementation of connections are the gear ratios. A smaller gear on the drive train connects to a larger gear in the transmission which is parallel to smaller gears in the differentials which are connected to larger gears which send rotational energy to the wheels.

Gate 3: Product Analysis

Coordination Review

On our last gate, we got a lower grade than we would have liked. For this gate, in order to hopefully improve on the quality of our work, we have decided to do much more of the gate as a team rather than splitting up the entirety of the written work. We have decided to meet for an hour after class on Mondays and Wednesdays from now on, in order to discuss what we are doing individually and to do some segments as a team. For example, in this gate we all created a model of one or two pieces of the engine in CAD on our own, but we created the assembly drawing together in order to check the dimensions and guarantee that the arrangement of the parts was correct. By working together more often than we did on the first two gates, we have also cut back on the possibility of there being a conflict due to a group member handing in late work. Everyone has to keep up to date rather than cramming the work in in the last several days, and even though we never had late work conflicts on earlier gates, this will prevent them from happening in the latter stages of this project.

The major issue which we had to overcome for this gate was time management. In the time we had to work on this gate, there have been several tests and an overall larger work load for each member in our group. This has put a stricter time limit than normal on us individually. By meeting immediately after class, we have made sure that we all can remain focused on the work which we have chosen to do before that day and what we need to do as a group.

Looking forward to the last two gates, the biggest obstacle is that we have fall recess in the midst of the time allotted to work on the fourth gate. Our plan is to get as much of the reassembly process done as possible on Saturday the 19th so that when we get back from break we do not have to find a large block of time to finish the work which we will have left to do for the gate. Any work that can be uploaded to the wiki during the break will be in order to cut back on the final time crunch as well.

As problems arise, they will be talked over as a group and if a unanimous decision can not be made, a majority vote will help decide the outcome of any conflicts as long as no one member of the group become target of unfair work.

Product Archaeology

There are exactly 387 components used to create this remote controlled vehicle. From fasteners, to supports, to larger functional parts, they all play a role in keeping the Hyper Speed RC car together and running smoothly. A detailed list of all of these components can be found on the page Exceed RC Buggy Component summary. In depth analysis on five specifics parts can be found on the page Exceed RC Buggy Product analysis. Auto CAD assembly drawings for the solid model can be found on the page Exceed RC Buggy Solid Modeling.

In determining the sizes, materials, and placement of all of these components, many important engineering decisions had to be made through analysis. One specific analysis process which was carried out was to determine the best gear ratios. Maximizing Gear Ratio is important due to limited space for gears. All of the subsystems are tightly knit so this analysis was likely carried out early on in the design so that the other scaled down components could fit together well. This analysis can be found on the page Exceed RC Buggy Engineering Analysis

Design Revisions

After carefully examining the processes by which this car was both designed and made, we have found several ways by which the product could be improved. These changes are all on the level of a subsystem or one of its components, as we were restricted from overhauling our product entirely. The pieces which we think need to be redesigned the most are the Plastic Body, Glow Plug, Controller Steering Knob, and Fuel tank support.

The fuel tank support tray is the easiest fix out of all of the design problems. As it currently exists, only one of the supports which connect it to the chassis are molded onto this piece of the frame. We believe it would be more economical to add the other four plastic pieces which connect it to the chassis to the mold used to create the piece. This would remove the need for the use of four other molds, and the four screws which attach the other supports to the tray. The only tradeoff from this is that the pieces would have to be more in the opposite direction which they are now, which would sacrifice strength. This is acceptable for this piece because it is supported in five locations and although almost all of the subsystems are connected to the tray, the attachments are meant more for positioning the subsystems than supporting their weight. So simply by creating a new mold, several other steps of the manufacturing and assembly process can be cut out, therefore decreasing production costs in the long time.

Gate 4: Product Explanation

Critical Project Review

For this gate, the main problem which we had was that our schedules did not make it easy to meet as an entire group much during the week after fall recess. We solved this by assigning Sean the presentation so he could work on it in his own time and the rest of us could put most of the time required for the gate in. The rest of us were able to meet for the reassembly while he was at work. Also, our plan to have everyone give Craig the work three days before the gate is due had to be pushed back to two days before this time. This is both because the reassembly took more time than we anticipated, and because there was not much work which needed to be divided. Otherwise, there have been no issues with group members not carrying their weight and doing their work in time.

Looking ahead to finishing the project, all that remains is the editing and finalizing step as our group presentation has been given already. Most of the simple fixes have already been implemented, such as reformatting a couple of earlier sections. In addition, we have realized through the feedback we have received that the level of detail which we have put in on the past few gates needed to be improved for the final technical document. We have the most work to do on the third gate but since there is not much homework due the final week of classes, we anticipate finishing the editing before we get into finals week, well before the due date.

Product Explanation

Since this product was designed with ease of disassembly and reassembly in mind, we did not face any major problems in reassembling it. The product was stored well so no fasteners or small pieces were lost, and no other pieces were broken since the disassembly. The steps by which the RC car was put back together are enumerated in the page for Exceed Hyper Speed Reassembly.

Through the entire project, we have found several flaws in the car, and ways to improve them. Also, we have thought of several ways to increase the functionality of the car. The revisions which we would like to make on a system level are found in the page for Exceed Hyper Speed Design Revisions.